«

102 PLATE CLXXVI. .

There are two varieties of this species : one kind being attwice the size of the other ; in every other respect they perfectlyagree. This Insect is commonly seen on still waters, in the Summer jwhen they cause a gentle agitation of the surface, by the quickslct* Sof their motions, and row along on their back, with their hinderlegs, which are formed for swimming. Both kinds are shown 1,1the Plate, Fig. I. and II. Fig . III. is the largest fort magnifiedto exhibit the curious markings of the Elytra.

PLAT^